Polyamides stabilized against degradation with copper salts and phosphine halides

ABSTRACT

POLYAMIDES STABILIZED AGAINST DEGRADATION BY HEAT AND OXIDATIVE EFFECTS, CONTAINING AS STABILIZER A COMBINATION CONSISTING OF (A) A COPPER COMPOUND AND (B) A TERTIARY PHOSPHINE DIHALIDE OF THE GENERAL FORMULA   R1-P(-X)2(-R2)-R3   WHEREIN R1, R2 AND R3, WHICH MAY BE DIFFERENT OR NOT, REPRESENT ALKYL, CYCLOALKYL, ARYL OR ARALKYL RADICALS OR R1 AND R2 TOGETHER REPRESENT AN ALKYLENE RADICAL AND R3 REPRESENTS AN ALKYL, CYCLOALKYL, ARYL OR ARALKYL RADICAL, AND X REPRESENTS CHLORINE, BROMINE OR IODINE.

United States Patent POLYAMIDES STABILIZED AGAINST DEGRADA- v Int. Cl. C08g 51/60, 51/62 U.S. Cl. 260-45.75 2 Claims ABSTRACT OF THE DllSCLOSURE Poly-amides stabilized against degradation by heat and oxidative effects, containing as stabilizer a combination consisting of (a) a copper compound and (b) a tertiary phosphine dihalide of the general formula wherein R R and R which may be different or not, represent alkyl, cycloalkyl, aryl or aralkyl radicals or R, and R together represent an alkylene' radical and R represents an alkyl, cycloalkyl, aryl or aralkyl radical, and X represents chlorine, bromine or iodine.

i The 'invention'relates to stabilised polyamides contain"- 'ing a combination of copper compounds and tertiary phosphine dihalidesas stabilisers and to a process for their production.

Shaped articles 'made of polyamides thathave been produced by polycondensation of diamines and dicarboxylic acids or of aminocarboxylic acids or by polymerisation of their lactams, for example filaments,bristles, foils, etc., are damaged by the action'of air and oxygen,

especially at elevated temperatures'This has'the effect of 7' reducing the" relative viscosity and impairing them'echanical strength and stretching properties of the polyamide. At the same time, the polyamide becomes increasingly brown 5 l "i It is known to protect polyamides against such damage by air and oxygen at elevated temperatures by the addition of stabilisers. The following compounds, for example, have already been proposed as stabilisers: Manganese salts of inorganic and organic acids, copper salts of inorganic and organic acids, derivatives of oxyacids of phosphorus, aromatic amines and phenolsr-For pref-- erence combinations of these groups of compounds with each other, or with compounds which have no stabiliser 'effect-ontheir own'have alsobeenused, e.g.-with alkali Patented Jan. 5, 1971 halogen compounds such as iodine, alkali metal halides, alkaline earth halides, halides of diflicultly volatile organic bases, phosphorous trihalides, phosphoroxyhalides or tin tetraiodide, which has an excellent stabiliser effect as such, also generally leads to discolouration of the polyamide.

Moreover, most of the halogen compounds previously used can be extracted with water so that their addition to polyamides which have to be freed from monomeric constituents by extraction with hot water, for example, polycaprolactam or copolyamides of caprolactarn, cannot be carried out before this extraction. Addition after the extraction, however, necessitates an additional working step since the polyamide has to be melted again in order that it may be mixed homogeneously with the sta-bilisers. The fact that the halogen compound can be extracted is also disadvantageous when the stabilised polyamide is brought into contact with water or aqueous solutions. Furthermore, when phosphorous trihalides and phosphoroxyhalides are used, an uncontrollable increase in the melt viscosity of the polyamide may occur due to partial cross-linking or branching and this increase in the melt viscosity leads to dilficulties in the working up processes, especially in the production of fibres.

It is an object of this invention to provide stabilised polyamides which do not show the disadvantages outlined above.

This object is accomplished by a polyamide, stabilised against degradation by heat and oxidative eitects, containing as stabiliser a combination consisting of:

(a) a copper compound in such an amount that 0.0001 to 0.2% by weight, based on the polyamide, of copper are present and (b) 0.001 to 5.0% by weight, based on the polyamide,

of a tertiary phosphine dihalide of the general formula wherein R R and R 'which may be difierent or not, represent substituted or unsubstituted alkyl, cycloalkyl, aryl, or aralkyl radicals, or R and R together represent analkylene radical and R represents an alkyl, cycloalkyl, aryl" or aralkyl radical, and X represents chonine, bromine,

or iodine.

It is a further object of this invention to provide a process for the production of polyamides, stabilised against degradation by heat and oxidative elTects, which comprises adding to the polyamides or to the polyamides forming starting materials a stabiliser combination consisting of: a

metal halides, alkaline'earth halides iodine, arylsulfonic- "acids and mercapto benzimidazole.

The stabilisers previously used have the disadvantage that either their] stabilising effect is not sufiicient, for: example, when Mn and Sn salts, phosphorous compounds,

distannanes or phenols are used, or that they are sensi tive to light, whichcauses discolouration of the polyamide in the course of time, for example when aromatic amines and phenols are used.

,The. addition of a. combination of" copper. salts and (a) a copper compound and (b) a tertiary phosphine dihalide of the general formula wherein R R and R which may be different or not, represent substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl radicals, or R and R together represent an alkylene radical and R represents a' substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl radical, and X represents Cl, Br or I.

The following are examples of tertiary phosphine dihalides which may be used according to the invention: the dichloride, dibromide and diiodide of tributylphos- 4 the polyamide, may be mixed with the polyamide melt during or after polymerisation or polycondensation, using known mixing apparatus such as extruders, kneaders or stirrers.

Polyamides are here understood to mean polyamides phine; the dichloride, dibromide and diiodide of tricyclo- 5 which are formed by polymerisation of lactams or by hexylphosphine; the dichloride, dibromide and diiodide polycondensation of diamines and dicarboxylic acids or of triphenylphosphine; the dichloride, dibromide and diamino carboxylic acids. iodide of cyclohexyldiphenylphosphine; the dichloride, In addition to the stabilisers, the polyamides may also dibromide and diiodide of phenyldibutylphosphine; the contain the usual additives such as pigments, dyes, light dichloride, dibromide and diiodide of diphenylbenzylstabilisers, optical brightening agents, fillers, such as glass phosphine; the dichloride, dibromide and diiodide of trifibre or asbestos fibre, lubricants and mould parting (a-chloroethyl)-phosphine; the dichloride, dibromide and agents, and plasticisers or crystallisation promoters. diiodide of tri (4 bromophenyl) phosphine; the di- The polyamides which have been stabilised according chloride, dibromide and diiodide of di (chloromethyl)- to the invention and which are particularly stabilised phenylphosphine; the dichloride, dibromide and diiodide against damage by oxidation at elevated temperatures, of diphenyl (4 hydroxy 3,5 di tertiary butylare very suitable for the production of commercial silk phenyl) phosphine; the dichloride, dibromide and difor fishing nets, drive belts, conveyor bands, tyre cords iodide of 1 butylphospholine (3); the dichloride, diand shaped articles which are subjected to heat treatment bromide, and diiodide of l-phenyl-phospholine-(B). with free access of air or oxygen.

These compounds are prepared in a simple manner by The following examples are to further illustrate the known processes by the addition of chlorine, bromine invention without limiting it. or iodine to tertiary phosphines EXAMPLE 1 Y R3P+X29R3PX2 5 1 kg. of a colourless polycaprolactam which has been or by addition of alkyl halides to monohalogen phosprepiilmd i usual manner and which has a relative phines .SOIUUOII viscosity of 3.12 (measured on a 1% solut1on R2PX+RXQ px 1n m-cresol at C.) is melted in a conventional screw extruder and at the same time homogeneously mixed and y r ly li ry ll n compo ndsf with various stabilisers. The stabiliser containing polythe tertiary Phosphifle dihalides it is Preferred to use caprolactam is spun into bristles of about 3 mm. diamthe phosphine diiodides because they are particularly eter, chopped up into a granulate and dried. The granulate effective and stableis then stored in a drying cupboard at 150 C. with free Tertiary Phosphifie dihalides are advantageously added access of air, and the relative viscosity is measured after in quantities of 0.001 to 5.0% by weight, preferably 0.01 144, 500 d 1;00() h ur to 10% y Weight, basfid 0n the p lyamide. The experimental results are shown in Table 1. Experi- Sllitable PP Compounds are the Salts of inorganic ments 7 to 9 are experiments carried out for comparison. acids, for example Cu(I'I)Cl Cu(I)Cl, Cu(II)Br EXAMPLE 2 Cu(I)Br, Cu(I)I, Cu(I)CN and Cu(II)SO the salts of organic carboxylic acids, for example Cu acetate, Cu 40 A mixture of 1.1 kg. of caprolactam, 35 g. of e-aminostearate and Cu benzoate, the salts of monovalent or caproic acid, 0.8 g. of acetic acid as chain breaking repolyvalent phenols, and also the complex compounds of agent and various stabilisers is polycondensed in an autosnch copper salts with ammonia, amines, amides, lacclave in the usual manner at a temperature of 270 C. tams, phosphites, phosphines and cyanides. The products obtained are spun as bristles of about 3 The copper compounds are advantageously added in mm. diameter, chopped up into a granulate, freed from such an amount that the polyamide contains 0.0001 to monomeric constituents by several hours boiling with 0.2, preferably 0.001 to 0.02% by weight, based on the Water, and dried. The colour and iodine content of the polyamide, of copper. polyamides obtained are shown in Table 2. In addition, The stabilisers may be added to the polyamide-forming the granulate obtained is stored as in Example '1 in a starting mixture before polymerisation or polycondensadrying cupboard at 150 C. with free access of air, and tion, and the polymerisation may then be carried out in the relative solution viscosity (measured as in Examknown manner either continuously or intermittently. ple 1) is measured after 144, 500 and. 1,000 hours. The

Alternatively, the stabilisers, either together or sep- ,results are again shown in Table 2. I arately, or if desired in the form of a concentrate in Experiments 8 and 9 are comparison experiments.

TABLE I Percent P.p.m. halogen Relative solution viscosity Cuin in the Colour Serial thepolypolyofthe Starting After After After No. Cu-componnd Mg. amide Halogen compound G. amide polyamide product 144 hr. 500'hr. 1,000 hr.

1 Cu(I)I'Ztri- 337 30 Triphenylphosphine diiodide-.. 2.0 0.1 colourless" 3.10 3 92 3.38 2. 94

phenylphos- 2 332%- 30 Tricyclohexylphosphine diiodide 2.1 3.14 3. 87 3.32 2.90 3. do..- 30 Tributylphosphine diiodide..." 1.8 3.11 3.90 3.32 2. 91 4 K3Cu(C Tricyclohexylphosphine diiodide 2.1 3.13 I 404 g 3. 44. 3.03 5. cn(1)1 30 do 2.1 3.11 3.76 3.24 2.31 6 Ou(II)acetate- 94 30 do 2.1 0. 3.12 3. 72- 3.20 2. 76 7 "i fig: 94 30 KI 1.3 0.1 Greenish 3.14 3. 64 3.12 i a'es Cu(DI 90 30 1.0 0.1 Greyish 3.12 .3.eo 3.10 4 2.65

brown. V 9 KaCu(CN)4 250 3.10 3.36 2. 41

6O Colourless 2. 90

TABLE I1 Con'e- Halogen Cu oonspending content tent of to p.p.n1. of the Relative solution viscosity the polyhalogen Colour polyamide Serial amide, in the of the (determined Starting After After After No. Cu-cornpound Mg. p.p.m. Halogen compound G. polyamide polyamide analytically) material 144l1r. 500 hr. 1,000hr.

1 Ou(I)I-2 tri- 337 30 Triphenylphos- 2.0 1,000 Colourless 740 2.78 3.16 2.88 2.52

phenylphosphinediiodide. phine.

30 Triphenylphos- 2.6 700 2.76 3.11 2.77 2.42

phinedibromide. 30 Tricyclohexylphos- 2.1 020 2.80 3.26 2.05 2.58

phinediiodidc. 30 Iributylphosphine- 1.8 720 2.77 3.20 2. 89 2.56

diiodide. 30 Tricyelohexyl- 2.1 900 2.76 3.23 2.93 2.60

phosphinediiodide. 6 Cn(II)acetate- 94 30 Triphenylphos- 2.0 1,000 do 730 2.74 3.15 2.86 2.53

11 0. phinediiodide. 7 d0 94 30 Traibuctlyphosphine- 1.8 1,000 (10 750 2.78 3.18 2.88 2.53

no 1 e. 8 do 94 30 KI 1.3 1,000 Greenish 100 2.80 2.78 2.41 2,16 9 Cu(I)I'2 tri- 337 30 Iodine 1.0 1,000 Brown 400 2.78 2. 94 2.60 2. 24

phenylphosphine.

lactams, phosphites, phosphines, and cyanides, in such 30 an amount that 0.0001 to 0.2% by Weight, based on the polyamide, of copper are present and (b) 0.001 to 5.0% by Weight, based on the polyamide,

of a tertiary phosphine dihalide of the general formula wherein R R and R Which may be different or not, represent substituted or unsubstituted alkyl, cycloalkyl, aryl or aralkyl radicals, or R and R together represent an alkylene radical and R represents an alkyl, cycloalkyl, aryl or aralkyl radical, and X represents chlorine, bromine or iodine.

2. The polyamide of claim 1, said tertiary phosphine dihalide being a tertiary phosphine diiodide.

References Cited UNITED STATES PATENTS 2,705,227 3/ 1955 Stamatofi 26045.7 3,180,849 4/1965 Thompson 26045.7 3,428,597 2/1969 Dikotter et a1. h 260--45.75

HOSEA E. TAYLOR, Primary Examiner US. Cl. X.R. 26037, 45 .7 

